Sine wave on the environment texture
That can be this kind of settings:

Base nodes (with X and Y centered from &quot;generated&quot; coordinates, using &quot;vector mapping&quot;)

Take the angle through &quot;separate X Y Z&quot; and &quot;artan2&quot; using X and Y.

Get the &quot;sin&quot;.

And compare it to Z value.


Tuning (in green above)

Multiply the angle with some value to have the wave amount.

Multiply Z to handle the wave height.

Use some value to tune the wave line height.



here a blend file for 2.8: